The objectives of this project are to establish REGISTERS OF INHERITED METABOLIC DISEASES (IMD) that will provide data for appropriate health-care providers to identify, classify, and track patients with IMD. Methodology developed to implement as accurate and complete register information as possible on two IMD (galactosemia and MSUD) will be transferable to other diseases. Tasks include: (1) ensure security of data and confidentiality of patient identity; (2) identify information sources from which diagnoses have been ascertained or potentially identified; (3) develop survey instruments to determine methodology of current data collection; (4) define data set(s); and (5) develop forms for collecting register information. Database management includes combining existent metabolic clinics' data, newborn screening bases, and yet to be determined data sources, to create as large as possible ascertainment not previously available. Potential uses of registers include diagnostic and research studies of: (1) treatment or classification; (2) morbidity and mortality; (3) incidence and prevalence; and (4) risks for offspring. Directories will be created to couple identification of individual physicians and/or groups involved in patient care and research with laboratories performing diagnostic tests. The resulting commercial registers will allow clinical personnel to access timely information linking health care providers and such IMD patients.